Polyurethane foams

ABSTRACT

Flame-retardant polyurethane foams are obtained by a process in which a tolylene diisocyanate (T.D.I.) is reacted with a polymeric polyol in the presence of a substance which is normally effective for the polymerisation of T.D.I. and an anti-aging additive such as a halogenated aliphatic phosphate, of which the following is a specification.

United States Patent [1 1 Fishbein et al.

[ Apr. 9, 1974 POLYURETHANE FOAMS [75] Inventors: John Fishbein, Marlow; Raymond W. H. Bell, Great Kings Hill; Anthony J. Clarke, Chinnor; Peter Merriman, Stratford-on-Avon, all of England [73] Assignee: Dunlop Holdings Limited, London, SW. 1, England [22] Filed: May 28, 1971 [21] Appl. No.: 148,171

[30] Foreign Application Priority Data June 19, 1970 Great Britain 30000/70 [5 U.S. C1 W, 260/25 AB,

Q 2- ,AM1 6Q A A BB 51 Int. Cl... C08g 33/02, C08g 22/Wc08 {75351 [58] Field of Search... 260/25 Aw, 2.5 AP, 2.5 A1, 260/25 AB, 77.5 NC, 2.5 AM, 2.5 BB

[56] References Cited UNITED STATES PATENTS 3,108,975 10/1963 Lambert 260/2.5 AB

3,336,242 8/1967 Hampson ,.260/2.5 AP 3,546,145 12/1970 Granger ..260/2.5 AP

FOREIGN PATENTS OR APPLICATIONS 1,155,768 6/1969 Great Britain 260/25 AW 908,337 10/1962 Great Britain 260/25 AW 1,807,953 6/1969 Germany 260/25 AW 1,478,759 4/1967 France 260/25 AW Primary Examiner-Donald E. Czaja Assistant Examiner-C. Warren lvy Attorney, Agent, or Firm-Clelle W. Upchurch 5 7] ABSTRACT 12 Claims, No Drawings POLYURETHANE FOAMS This invention relates to flexible polyurethane foams, particularly to flame-retardant polyurethane foams, and to methods of making them.

Conventional polyurethane foams, particularly those derived from polyethers, have little inherent retardance to burning (flame-resistance), and in view of the widespread use of polyurethane foams in mattresses, cushions and other upholstery there exists a demand for flame-retardant products. Previous proposals for reducing the inflammability of flexible polyurethane foams have included the incorporation in the foamforming reaction mixture of certain conventional flame retardants, for instance halogenated alkyl phosphates. However, these materials have either tended to be lost by evaporation during the foam-forming reaction or, if of sufficient molecular weight to preclude substantial loss by evaporation they have, because of their relatively high density, tended to concentrate, in the lower regions of foam products during manufacture, especially where manufacture is by a continuous, free-rise method producing a foam loaf. Consequently, in order to ensure that sufficient flame retardant is included in the upper regions of the loaf it has been necessary to incorporate in the foam-forming reaction mixture an amount of such conventional flame retardant substantially in excess of that which would be required if the retardant could be distributed evenly throughout the foam loaf.

We have now found, according to the present invention, that flexible flame-retardant polyurethane foams can be obtained by a process in which a polymeric polyol is reacted with a tolylene diisocyanate (T.D.l.) in foam-forming reaction mixture which contains: (a) as a foam modifier a substance normally effective as a catalyst for the polymerisation of tolylene diisocyanate, and (b) an anti-ageing additive substantially to limit any deleterious effect of the foam modifier on ageing of the polyurethane foam.

By polymerisation of tolylene diisocyanate above is meant in particular the polymerisation of three molecules of TD]. to produce a cyclic trimer usually of isocyanurate or perhydrotriazine structure. It is not known for certain whether the foam modifier in the present invention does in fact result in the polymerisation of the T.D.l in the reaction mixture, but it is believed that polymerisation does occur, at least where pure T.D.l. is initially present.

A particular advantage of the foams of this invention is that when subjected to flame they give off much less smoke than do conventional flame-retardant foams. This is a most valuable practical advantage because emission of noxious smoke and fumes when subjected to flame is one of the principal shortcomings of such conventional flame-retardant foams.

Substances suitable as catalysts for the polymerisation of T.D.l., in particular polymerisation to give trimers of isocyanurate structure, are shown in the literature such as Saunders, J. R. and Frisch K. C. Polyurethanes, Chemistry and Technology, Part 1, pages 94-97, and 212, Beitchmann, B. D. Rubber Age, Feb., 1966, Beitchmann B.D.l. & EC Product Research and Development, Vol. 5, No. 1, pages 35-41, Mar. 1966, and Nicolas, L. and Gmitter, G. T. 1. Cellular Plastics, Vol. 1, pages 85-95 (1965).

Suitable substances are as follows:

a). Organic bases and salts and derivatives thereof, such as tertiary amines. Examples are triethylamine, tetramethylguanidine, nickel derivatives of bipyridyl and N-alkyl morpholines.

b. Alkaline inorganic compoundssuch as hydroxides, carbonates, oxides, bicarbonates and peroxides, and basic salts of weak inorganic acids. Examples are sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium sesquicarbonate, sodium peroxide, sodium tetraborate (borax), sodium stannate, sodium tungstate, sodium molybdate and sodium silicate.

c. Alkali metal and other basic salts and derivatives of organic acids, phenols, monoor dicarboxylic acids of aliphatic or aromatic nature, and of other organic acids such as phthalimide, diethyl phosphite,-acetic acid, halogenatedacetic acids, phenol (C ll -OH) and other hydroxy-aromatic compounds, and alcohols. The carboxylic acid salts can be of acids having 6-20 carbon atoms, for example salts of octoic, 2-ethyl hexoic, benzoic or oleic acids. Examples are sodium acetate, sodium formate, sodium phenate, sodium salts of monochlorodichloroand trichloroacetic acids, sodium methoxide, lead heptane carboxylate (lead octoate), calcium naphthenate'and sodium benzoate.

The potassium and lithium compounds corresponding to the sodium compounds referred to above under headings (b) and (c) can be used. The corresponding alkaline earth compounds can also be used, though their efficacy is somewhat affected by their limited solubility.

d. Onium compounds of nitrogen, phosphorus, antimony, sulphur and selenium. Examples are tetramethyland tetraethylammonium hydroxides, benzyltriethyl-ammonium hydroxide, benzyltrimethylammonium hydroxide and tetraethyl phosphonium hydroxide. Of course, the particular substance or substances used as foam modifier in the process of the present invention shouldbe such that there is no undesirable effect on the foamforming reaction. 1

The foam modifiers of particular interest in the process of the present invention arebasic substances, preferably readily soluble in water, and it is to such foam modifiers that the following description particularly relates.

The amount of the foam modifier incorporated depends upon the particular modifier used and the nature of the components of the foam-forming reaction mixture. Although larger amounts can be used, it is not, in general, necessary to use an amount greater than 1% by weight of the polyol component, and the preferred amount is 0.05l%, especially 0.25%. However, where the foam modifier is a tertiary amine the preferredamount is somewhat greater, and amounts of up to 5% or even more may be found necessary for good results. The foam modifier, where water-soluble, is conveniently incorporated as a solution in water, for example in the water component of the foam-forming reaction mixture.

The polyol used in the production of the flameretardant foams of this invention is normally a polyether polyol having a high reactivity, though polyesters can be used. Suitable polyether polyols are those having a substantial proportion of primary hydroxyl end groups, usually referred to as ethylene oxide-tipped polyols. However, other polyols can be used, and good results have been obtained using triols (nontipped polyols) such as those sold under the Trade Mark Varanol CP.3720. Suitable ethylene oxide-tipped polyols are those in which the primary hydroxyl groups comprise 20, 30., or 40% to 70% (for example 50-60%) of the total number of hydroxyl groups in that polyol. Where the polyol is a triol a suitable molecular weight is in the range 3,000-6,000.

A- suitable polymeric polyol is one'obtained by reacting a substance having a plurality of active hydrogen atoms with an alkylene oxide (for instance propylene oxide or a mixture of propylene oxide and ethylene oxide), and subsequently reacting the product thus obtained with ethylene oxide so as to introduce the terminal primary hydroxyl groups. Polyether polyols of this type are commercially available under the trade name Desmophen 3900 (which is a polyether triol of very high activity having a mean molecular weight of 4,5005,l and a hydroxyl number of 33-37), and Propylan M.l2 described below with reference to the Examples.

The flame retardant foams of the invention can be, for example, foams of density up to 64 kg/m*, especially having densities in the range 16-64 kg/m.

There is a marked tendency for the foams of this invention to shrink after'being made due to closed cells in the foam. This can be overcome by mechanically squeezing or crushing the foam as is well known to those skilled in the art. However, we have found that shrinkage of the flame-resistant foams of the invention can be substantially obviated by the use of a polyether polyol derived from ethylene oxide in which at least some of the oxyethylene groups in the polyol molecule are in non-terminal positions. These subsidiary polyols which can for example be diols or triols, can contain from 20-80% (especially 40-70%) by weight of oxyethylene groups. Examples of suitable subsidiary polyols are the commercial products G978 of Lankro Chemicals Limited. The subsidiary polyol can be used in any suitable proportion with the major polyol, but we have found it to be effective in substantially obviating the formation of closed cells if it is used in an amount of from 2-40 (for example 4-15) parts of the total polyol component of the foam-forming reaction mixture. Care should be taken in the amount of the subsid- The subsidiary polyol is preferably fed to the mixer for the foam-forming reaction mixture as a separate stream, though satisfactory results have been obtained where it has been previously blended with the major polyol and the blend fed to the mixer.

It has further been found according to the present invention that the ageing properties of the polyurethane foams can be improved, especially where the foam modifier is a substance containing an alkali metal, for

instance sodium or potassium salts of phenols, or inorganic or carboxylic acids, or alkali metal hydroxides, or other basic substance, if there is incorporated in the polyurethane foam-forming reaction a neutralising anti-ageing additive, for instance a labile halogencontaining substance.

Suitable anti-ageing additives are as follows: I a. Halogen derivatives of phosphorus acids such as phosphoric, phosphorous and phosphonic acids.

Thus, the additives can be aliphatic phosphate esters, such as chloroand bromoderivatives of trialkyl orthophosphates, for example compounds of the formula R PO where R is a halogenated preferably polyhalogenated alkyl group of two, three or four carbon atoms. Examples of suitable anti-ageing additives are a) Halogen derivatives of phosphorus acids such as orthophosphoric acid, phosphorous acid. Examples are tris bromopropyl phosphate, tris chloropropyl phosphate, tris bromoethyl phosphate, tris chloroethyl phosphate, tris 2,3-dibromopropyl phosphate, (T.B.P.P. which is particularly effective), tris 2,3-dichloropropyl phosphate.

Other examples are:- haloalkyl-alkenyl phosphates e.g., diallyl-2,3-dibromopropyl phosphate, bis (2,3- dibromopropyl) allyl phosphate and bis (2,3- dichloropropyl) allyl phosphate; 2-bromo diglycolyl phosphate; haloalkyl phosphonates e.g., bis (2- bromoethyl) phosphonate; diallyl phenyl phosphonate; alkyl phosphonium chlorides e.g., tetrakis (hydroxymethyl) phosphonium chloride; haloalkyl phosphites e.g., tris chloroethyl phosphite and tris bromoethyl phosphite.

b. Halogen derivatives of aliphatic (acyclic or alicyclic) or aromatic hydrocarbons Examples are derivatives of paraffins such as propane, e.g., 1,2,3-tribromopropane; halogenated benzenes and substituted benzenes, e.g., chloro-benzenes and pentabromotoluene; chlorinated and brominated polyphenyls, e.g., biphenyl, diaminoethoxy polyhalogenated biphenyl, dihydroxy hexachloro biphenyl and dihydroxy octachloro biphenyl; halogenated cycloalkanes e.g., perchloropenta-cyclodecane and -cyclododecane, derivatives of cyclopentadiene and adducts thereof such as adducts of hexachloroor hexabromocyclopentadiene.

c. Halogen derivatives of aliphatic and aromatic hydroxy compounds as follows:

Examples are derivatives of Alcohols, Examples are dichloro-pentaerythritol, pentaerythritol dichlorohydrin, chloromethyl pentaerythritol, pentahalophenoxy- 2,3-propane diol, e.g., dibromo neopentyl glycol and 2( pentachlorophenoxymethyl )2-ethyll ,B-propane diol,

Bisphenols, Examples are halogenated bisphenol A (2,2-diphenyl propane), e,g., 2,2-bis(4-hydroxy-3,5 dibromophenyl) propane, tetrachloro bisphenol A, epoxylated polyhalobisphenols,

Hydroquinones e.g., droquinone. d. Halogen derivatives of silicon compounds e.g., tetra (pentabromophenoxy) silane.

e. Halogen derivatives of ethers.

Examples are pentabromophenyl allyl ether, triepoxylated tetrachlorohybromophenyl allyl ether, halomethylated diaryl oxides and 1,2 bis (2,6-dichloro-4-alkoxycarbonyl-phenoxy) ethane.

f. Halogen derivatives of alkylene oxides e.g., trichloropropylene oxide.

Although many of the compounds referred to above are themselves flame retardants and they contribute towards the flame retardance of the foams, their effect in this direction is only minor and the flame retardance of the foams is due in the main to the use of the foam modifier. The amount of anti-ageing additive to be used depends of course upon the particular inhibitor and also the type of foam in which it is to be used. However, in general an amount of O.5-4 parts (especially l.53 parts) per hundred parts of the polyol component has been found to be effective. Such amounts are much less than the amounts in which, for example T.B.P.P. is conventionally used as a flame retardant additive usually about l5-20 parts per hundred of polyol. Where an organic bromo compound is used as the additive, it has been found that effective amounts are those corresponding to an amount of up to 0.25% (for example 0.05-0. 1%) by weight of bromine per 100 parts of polyol component. Where the additive is a chlorocompound the effective amounts are those corresponding to an amount of up to 0.5% (for example 0.10.2%) by weight per 100 parts of polyol component.

The anti-ageing additives are in general covalent organic' compounds which contain labile halogen atom or atoms. Such compounds can lose their labile halogen (for example, as a result of interaction between the halogen and alkali metal ions). The additives should be such that neither they, nor the residual substance left after loss of the labile halogen, have an undesirable effect on the reactions in the foam-forming reaction mixture. It is thought that the preferred additives, referred to above, probably do not lose their halogen until the early stages of the foam-forming reaction are complete, but that they then lose their halogen (perhaps due to the exothermic heat produced in the reaction) which can then combine with alkali metal ions in the reaction mixture and thereby preclude their interference with the reaction mechanism or deleterious effect on the foam product.

Small amounts of amine catalysts may be used in the process of the invention, though it has not been found essential to use them where the polyol is an ethylene oxide-tipped polyol; but they are more necessary when using non-tipped polyols. Examples of tertiary amines which can be used are, for example, dimethyl ethanolamine, N-methyl and N-ethy] morpholines, triethylaminc, and triethylene diamine (also known as 1,4- diazobicyclo 2,2,2-octane).

Under certain circumstances, for example when harder foams are required, cross-linking agents may be employed. Examples of suitable cross-linking agents are hydroxy amines, for example triethanol-amine and tetrakis N beta-hydroxypropyl ethylene diamine (sold under the trade name Quadrol); low molecular weight polyols, such as tetrols, hydroxyethers, for example tris-hydroxypropyl glycerol, and ortho-dichloro methylene bis-aniline.

In general the polyisocyanate and polyol components can be used in amounts such that the isocyanate index is of a normal value, for example in the range 100-1 10. However, isocyanate index values outside that range can be used if desired, but it has not been found necessary to exceed a value of 150.

The T.D.l. can be in a substantially pure state. Where T.D.l. is referred to herein it can contain one or more isomers thereof. For example, it can be tolylene-2,4- diisocyanate, tolylene-Z,-diisocyanate, or a mixture 6 thereof, for instance in the proportions 65:35 (65:35 T.D.I.) or, preferably, :20 T.D.I.) by weight.

The T.D.l. can be, for example, crude T.D.l. or T.D.I. in polymeric form.

Crude T.D.l. is the product obtained by reacting the appropriate diamine-toluene with phosgene without any substantial purification. It is believed to contain material of polyurea and polybiuret structure. Where a mixture of 2,4- and 2,6-diamino-toluene is used, the crude T.D.l. contains the corresponding 2,4- and 2,6- diisocyanates.

Polymeric T.D.l. is normally of uretdione or isocyanurate structure. It can be obtained from pure T.D.l. in a separate preliminary reaction using polymerisation techniques well-known in the art and using catalysts referred to herein.

It has been'found that the use in the process of the invention of large quantities of polysiloxaneoxyalkylene block copolymers should be avoided as they can detract from the flame-retardant properties of the polyurethane foams obtained. If a polysiloxaneoxyalkylene block copolymer is used it should preferably be in an amount less than 0.1% and preferably not more than 0.05%. However, small proportions of a polydimethyl siloxane as used in the Examples below is not objectionable, for example up to 0.1% by weight of the weight of the polyol component. Even larger quantities can be used if desired, and satisfactory foams have been obtained using amounts as follows:

Viscosity of silicone Amount (parts per of polyol) 2 centistokes 0.5-4 5 centistokes 0.025-0.25 l0 centistokes 0.05-0.l

reaction mixture is moulded and allowed to cure withv out the application of heat.

Moreover, the foams of the invention aresuitable for use in flame lamination to textile and other substrates.

Although it is not intended that the present invention should be construed with reference to any particular theory, it is thought that the foam modifier has the effect of producing a polyurethane foam having a structure different from that obtained in the absence of the foam modifier such that when subjected to flame the foam tends to collapse and thereby presents a reduced surface area to the flame. This view is supported by observation of what happens to a foam of the invention when subjected to a flame. For example, when'a lighted match is placed on a block of the foam the portion subjected to the heat of the flame readily melts or decomposes and retracts away from the flame but without any sustained burning. I

The invention is illustrated by the following Exampics, in which flexible flame-retardant polyurethane foams are obtained by the one-shot or single stage method.

The meanings of various Trade Names used in the Examples are as follows: Propylan M.l2 is the Trade Name of a polyether polyol sold by Lankro Chemicals Limited, and which is believed to be a poly(oxypropylene) poly(oxyethylene) triol having the following characteristics:

about 5000 35-37 I about 12-13% by weight It has a high proportion of primary hydroxyl end groups.

6.978 is an abbreviation for Development Polyol 6.978 sold by Lankro Chemicals Limited. It is used in the Examples as an anti-shrinkage agent, and is believed to consist essentially of a poly(oxyethylene) poly(oxypropylene) triol based on a glycerol starter and having a molecular weight of about 2,800, a hydroxyl number of 53-59 and a poly(oxyethylene) content of about 64% by weight. The proportion of primary hydroxyl groups: secondary hydroxyl groups in this polyol is believed to be in the ratio 40:60.

It will be seen that in Example 3 the polyol component contained a third polyol (as a cross-linking agent) referred to as Quadrol" which is believed to consist essentially of the compound: (CH CH(OH)CH NCH --CH,N(Cl-l -CH(Ol-l)--CH In the Examples the silicone MS.200/ is a commercial silicone oil having a viscosity of 5 centistokes and believed to be a dimethyl siloxane homopolymer, and the tris-dibromopropyl phosphate (T.B.P.P.) antiageing additive was used in the form of the commercial product Bromkal P.67. The T.D.l., except where stated otherwise, was 80:20 T.D.l. The hardness values were obtained under the test of BS3667. Reference in the Examples simply to catalyst is to the foam modifier.

EXAMPLE 1 A flexible, free-rise polyurethane foam was obtained using the following formulation:

Propylan M.l2 V 90 6.978 Polyol Component Water 3 Sodium phenate 0.4 T.B.P.P. 2 Silicone MS.200/5 0.05 T'.D.l. 36.5

In this Example, and in the other Examples, the amounts of the ingredients are shown in parts by weight.

The procedure used to make the foam was as follows.

First, the silicone was dispersed in 2.5 parts of the Propylan M.l2 polyol so as to provide a 2% solution; and the sodium phenate was dissolved in all of the water component. The remainder of the polyol component was then mixed with the T.B.P.P. and the polyol dispersion of the silicone by high speed stirring for 20 seconds. The aqueous solution of the sodium phenate was then added to the mixture and the whole was stirred for a further seconds. Then the T.D.l. was added and the stirring was continued fora further 8 seconds, at the end of which time the resulting foamforming reaction mixture started to cream and was immediately poured into an open mould.

The rise of the foam was completed in 90 seconds, and the foam was tack-free at the end of about 15 min- EXAMPLE 2 A flexible, free-rise polyurethane foam was obtained using the following formulation and the procedure described in Example 1:

Propylan M.l2 i 6.978 Polyol Component l0 Water 4 Sodium phenate 0.3 Silicone MS.200/5 0.05 T.B.P.P. 2 T.D.l. 46.5

The foam had a density of 24 kg/m and a hardness of 7-8 kg. and did not shrink on cooling.

EXAMPLE 3 Aflexible, free-rise polyurethane foam was obtained using the following formulation and the procedure described in Example 1;

Propylan M.l2 82.5 6.978 Polyol Component 12.5 Quadrol 5.0 T.B.P.P. 2 Water 4 Silicone Ms.200/5 0.05 Sodium phenate 0.25 T.D.l. 52.4

The foam had a density of 25.0 kg/m and a hardness of 13-15 kg. and did not shrink on cooling.

EXAMPLE 4 A flexible, polyurethane foam cushion wasobtained by a cold-moulding technique using the following formulation:

Propylan M. l 2 6.97 8

Polyol Component Water 3 Sodium phenate 0.5 Triethylamine 0.4 Silicone MS.200/5 0.05 T.B.P.P. 2 T.D.l. 36

The foam-forming reaction mixture, obtained using EXAMPLE 5 A flexible, free-rise polyurethane foam was obtained using the following formulation and the procedure described in Example 1;

Propylan M. l 2

6.978 Polyol Component Water 3 Sodium phenate Continued T.B.P.P. 2 T.D.1. 41.2 Silicone MS.ZO/5 0.05

The foam had a density of 29 kg/m and a hardness of 10 kg. and did not shrink on cooling.

EXAMPLE 6 A flexible, free-rise polyurethane foam was obtained using the following formulation and the procedure described in Example 1, the triethylamine being dissolved in the polyol:

Propylan M.l2 (Polyol Component) 100 Water 4.5 Sodium phenate 0.25 Triethanolamine 0.5 Silicone MS.200/ 0.05 T.B. P.P. 2 T.D.l.

EXAMPLE Mean 14 29 13 22 29 extent burned (m Burning 10 22 13 24 12 time (seconds) Burning 1.32 1.0 0.91 2.4 rate (mm/second) Besides their excellent flame-resistance, the foamsof these Examples were found to have high resilience more than 50% as measured by the falling ball rebound test and to show a relatively linear load-deflection relation.

EXAMPLES 7-14 Further flexible polyurethane foams were obtained using the procedure of Example 1 and the following formulations.

The foam of each of Examples 7-14 was found to be self extinguishing when tested according 14 ATM D l- 692/67T. That test was used for the products of all the following Examples except if stated otherwise.

Example 7 was repeated using the 6.978 in amounts of 7.5, 8.5, 9, ll, 12 and 13.5 parts, instead of the 10 parts used in the Example. In each case the amount of Propylan M.l2 used was such that the total weight of Propylan M.l2 and'G.978 was 100 parts. The foam products obtained in each case were self-extinguishing.

EXAMPLES 15-18 Example 7 was repeated but using the following labile halogen compounds instead of the T.B.P.P. Example 15 tris 2,3-dichloropropyl phosphate (as the commercial product Fryol F.R.2 2 parts); Example 16 tris ,B-chloroethyl phosphate (4 Parts); Example 17 1,2,3-tribromo propane (1.2 parts); Example 18 dibromo-neopentyl glycol (2 parts); (In Example 18 the amount of T.D.l. was increased to 37.6 to take account of the hydroxyl groups in dibromo-neopentyl glycol).

The foam product of each of these Examples was self-extinguishing, and did not suffer deterioration on heat ageing for 16 hours at 140C. However, in comparative Examples in which the halogen compound was omitted, the foam products had deteriorated so much at the end of 16 hours heat ageing that their relevant physical properties could not be measured.

EXAMPLES 19-21 These Examples illustrate the use of anti-shrinkage agents other than the polyol 6.978 to obviate shrinkage of flexible foam products.

The procedure and formulation of Example 7 was repeated except that the following amounts of antishrinking agents were used instead of the 6.978.. In each case the total amount of Propylan M. l 2 and antishrinkage agent was 100 parts. Example 19 Polyol R.16l 101 1.5 (for example 11.5) parts; Example 20 Polyol 1138 7-9 (for example 7) parts; Example 21 Polyethylene glycol (PEG 600) 10-1 1.5 (for example mp ns- Polyol R161 and Polyol DP 1138 are respectively polyether triols sold by Union Carbide Corporation and Lankro Chemicals Limited. They have molecular weights in the range 2,5003,500 and po1y(oxyethylene) contents of about and 79% by weight. The foam products obtained were self-extinguishing.

EXAMPLE 22 This describes the production of a flexible polyurethane foam moulding by the cold cure technique using a typical formulation of the present invention.

Example No. 7 8 9 1O l1 l2 l3 Catalyst Sodium Hydroxide Sodium Carbonate Sodium Sodium Benzyl trimethyl Potassium (anhydrous) Stannate Formate ammonium phenoxide Phenate (Na SnO 3H O) (parts) 0.15 0.25 0.4 0.2 0.5 0.4 0.5 0.45 Propylan 9O 90 90 90 92.5 90 90 M.l2 6.978 l0 l0 l0 l0 10 7.5 l0 10 Water 4.5 4.5 4.5 4.5 4.5 4.5 3 3' T.B.P.P. 2 2 2 2 2 0.4 2 2 Silicone 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 MS.200/5 T.D.1. 54 4 54 54 54 54 36.2 36.2 36.2 Propamine A 0.2 0.2

Foam Density 21 21 21 31 31 30 30 30 Propylan M.l2

Propylan M. 12 (288g) was blended with 12g. of polyol 6.978, 9 g. sodium carbonate solution (20g. Na,CO in 280g. water), 0.9 g. Dabco 33LV, 0.69 g. silicone MS.200/5 and 3.0 g. 98% pure triethanolamine. The blend was mixed with a high speed stirrer for seconds, 30 g. trichlorofluromethane was added and stirring continued for a further 10 seconds. 1 14 g. of T.D.l. was then added and further stirred for 10 seconds. The mixture was then poured into a mould having a surface temperature of 58C. The mould lid was clamped into place and the moulding left to cure without the application of heat for 10 minutes. The moulding obtained was of good appearance its density was 37 ltg/m and the foam was self-extinguishing.

EXAMPLE 23 This Example illustrates the use of sodium salts of halogenated acetic acids as catalyst. Using the procedure of Example 1 flexible, free-rise foams were obtained from the following formulation.

85.5 6.978 Polyol Component 12.5 Polyol EDPJOO 2 Water 4.5 Sodium monochloro acetate (S.M.C.A.) 0

Propamine A 0.4

T.B.P.P. 2 Silicone MS.200/5 0.05

T.D.l. 63

The foam density was 21.9 kg/m and the burned length was 22 mm.

The polyol EDP.500 is a low molecular weight crosslinking tetrol, believed to contain ethylene diamine as starter nucleus and having a molecular weight about 500.

EXAMPLES 24 and 25 EXAMPLE 26 Example 23 was repeated but using tetramethyl guanidine (0.3 part) as catalyst instead of the S.M.C.A., and 0.3 part of Dabco 33 LV instead of the Propamine A. The flexible foam obtained was self-- extinguishing.

EXAMPLE 27 Tetramethylammonium hydroxide was used as catalyst in the following formulation to produce a flexible foam.

Propylan M.l2 95 6.978 5 Water 4.5 T.D.l. 61.5 Silicone MS.200/5 0.05 (CH N. OH 0.34

The foam obtained was self-extinguishing.

ln a comparative Example withour T.B.P.P. the foam, though self-extinguishing, lost its flame resistant properties after heat ageing at 140C. for 4 7% hours.

EXAMPLES 28 and 29 These examples illustrate the use as the major polyol of a poly (oxypropylene) poly(oxyethylene) triol sold by The Dow Chemical Company under the Trade Mark Varanol CP-3720. This polyol has a molecular weight of about 3500 and is believed to have a poly( oxyethylene) content, substantially in non-terminal positions, of about 10-1 1% by weight.

Flexible foams were obtained from the following formulations:

Daltogard WP is triphenyl phosphite, and Silicone L-546 is a polydimethyl siloxane poly(oxyalkylene) block copolymer.

EXAMPLE 30 This example illustrates the use of co-catalysts with the T.D.l. polymerisation-type catalyst. A flexible foam was obtained from the following:

Propylan M.l2 92.5 6.978 7.5 T.D.l. (135 index) 66.5 Water 4.5 T.B.P.P 2 Daltogard WP l NaOH 0.15 Propamine A 0.2 Silicone MS.200/5 0.05

The foamproduct was self-extinguishing, mean extentburned being 43 mm.

EXAMPLE 3i Example 30 was repeated but using 02 part of N,N-dimethylbenzylamine in place of the Propamine A. The product was self-extinguishing, mean extent burned being 54 mm.

EXAMPLE 32 lsophorone diisocyanate (lDI) was used in conjunction with the T.D.l. to provide a flexible foam.

Propylan M.l2 6.978 10 T.D.l. 53.5 lsophorone D1 15 Water 4.5 T.B.P.P. l Napoa 0.2 Propamine A 0.2

Silicone MS.200/S A crude M.D.l. sold under the Trade Mark Isonate 143-L, and believed to be a carbodiimide-modified M.D.l. was used in conjunction with T.D.l.

Propylan M.l2 95 0.978 5 T.D.l. 45.5 M.D.l.

Water Daltogard WP Na CO Propamine A Silicone MS.200/5 NCO index 135 The foam product was self-extinguishing, mean extent burned being 17 mm.

EXAMPLES 34-43 Ten further flexible foams were obtained using various catalysts in the following formulations. Compara tive foams using the same formulations but without T.B.P.P. and Daltogard WP were also produced.

On hot oven ageing at 140C. it was found that the comparative foams has substantially lost their flameretardant properties after 5 hours, and after 16 hours they had deteriorated so much that their relevant physical properties could not be measured. On the other hand, the foams of the invention had retained their flame-retardant properties, and their physical properties were only little worse then before ageing. Indeed, their tensile strength and elongation at break were better.

1. only from 2% to by weightof the total polyol of a polyol which contains from 20% to 80% by weight oxyethylene groups with some of the oxyethylene groups being in a non-terminal position and having a molecular weight of from about 300 to 3,500,

2. a catalyst which is capable of promoting trimerization of tolylene diisocyanate, and

3. from about 0.25 to 4 parts per 100 parts total polyol of a compound containing labile halogen which inhibits heat ageing of the foam which may be caused by any trimerization promotor remaining in the foam after it is formed.

2. The process of claim 1 wherein the subsidiary polyol contains 40-70% by weight oxyethylene groups.

3. A process according to claim 1, in which the compound of (3) is a halogenated aliphatic phosphate ester.

4. A process according to claim 3, in which the ester is a chloroor bromoderivative of a trialkyl orthophosphate.

5. A process according to claim 4, in which said ester is tris 2,3-dibromopropyl orthophosphate.

6. A process according to claim 1, in which the (2) is a compound selected from the group consisting of alkali metal hydroxides, alkali metal salts of weak inorganic acids and alkali metal salts of weak organic acids.

7. A process according to claim 1, in which (2) is a compound selected from the group consisting of sodium phenate, potassium phenate, sodium acetate, potassium acetate, sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide.

8. A process according to claim 1, in which (2) is present in an amount of 0.05-1% by weight of the polyol component.

Example N0. 34 35 36 37 38 39 40 41 42 43 Catalyst Sodium Sodium Sodium Sodium Sodium Lith- Potas- Potas- Sodium Ni(O) (bi Tung- Molyb- Ace- Bicarbsesquiium sium sium Silicate pyridyl),

state date tate onate carbon- Hydro- Ace- Hydrate xide tate oxide No. of parts of 0.8 0.8 0.6 0.2 0.2 0.42 0.6 0.2 0.4 0.4 catalyst Propylan M.l2 9O 90 90 90 90 90 90 90 90 95 0.978 l0 l0 l0 10 10 l0 l0 l0 l0 5 Water 4.5 4.5 4.5 4.5 4.5 4.32 4.5 4.5 4.5 3 T.B.P.P 2 2 2 2 2 2 2 2 2 2 Daltogard WP l l l l l l l l l l MS.200/5 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 T.D.l. 61.5 6 1.5 61.5 66.5 66.5 61.5 61.5 61.5 61.5 43.4 Mean Extent burned mm. 54.8 75 42.3 28.8 17.5 47.4 53.7 32.5 76.2 (BS 4735) The sodium sesquicarhoante was used in the form of an aqeous solution prepared by dissolving equimolar amounts of sodium carbonate and sodium bicarbonate in water: this solution was used directly in the form formulation without isolating the sesquicarbonatc.

All the foam products had densities in the range lJ-25 kg/m. ln Example 43 there was used 0.6 part of N-elhyl morpholine.

We claim:

l. A method of reducing the smoke produced by a foam when subjected to a flame and for reducing the tendency of the foam to shrink after it has been made which comprises including in a foamable reaction mixture containing tolylene diisocyanate, a blowing agent and a polyester or an ethylene oxide tipped poly (alkylene ether) polyol containing from 20% to primary hydroxyl groups, and

' 9. A process according to claim 1, in which the tolylene diisocyanate reacted with the polyol is the product obtained by the interaction of diamino tolylene with phosgene without substantial purification.

10. A process according to claim 1, in which the tolylene diisocyanate has been previously polymerised, at least partially.

11. A process according to claim 1, in which the polyol (1) is a poly(oxyethy1ene) poly(oxypropylene) polyol whose poly(oxypropylene) content hasamolecweight of the total polyol component of the foamular weight in the range SOD-2,000. forming reaction mixture.

12. A process according to claim 1, in which the i l 7 polyol (1) is present in an amount of 4-15 parts by 5 a: 

2. a catalyst which is capable of promoting trimerization of tolylene diisocyanate, and
 2. The process of claim 1 wherein the subsidiary polyol contains 40-70% by weight oxyethylene groups.
 3. A process according to claim 1, in which the compound of (3) is a halogenated aliphatic phosphate ester.
 3. from about 0.25 to 4 parts per 100 parts total polyol of a compound containing labile halogen which inhibits heat ageing of the foam which may be caused by any trimerization promotor remaining in the foam after it is formed.
 4. A process according to claim 3, in which the ester is a chloro- or bromo- derivative of a trialkyl orthophosphate.
 5. A process according to claim 4, in which said ester is tris 2,3-dibromopropyl orthophosphate.
 6. A process according to claim 1, in which the (2) is a compound selected from the group consisting of alkali metal hydroxides, alkali metal salts of weak inorganic acids and alkali metal salts of weak organic acids.
 7. A process according to claim 1, in which (2) is a compound selected from the group consisting of sodium phenate, potassium phenate, sodium acetate, potassium acetate, sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide.
 8. A process according to claim 1, in which (2) is present in an amount of 0.05-1% by weight of the polyol component.
 9. A process according to claim 1, in which the tolylene diisocyanate reacted with the polyol is the product obtained by the interaction of diamino tolylene with phosgene without substantial purification.
 10. A process according to claim 1, in which the tolylene diisocyanate has been previously polymerised, at least partially.
 11. A process according to claim 1, in which the polyol (1) is a poly(oxyethylene) poly(oxypropylene) polyol whose poly(oxypropylene) content has a molecular weight in the range 500-2,000.
 12. A process according to claim 1, in which the polyol (1) is present in an amount of 4-15 parts by weight of the total polyol component of the foam-forming reaction mixture. 